DESCRIPTION (provided by applicant Prevalence of physical activity at the recommended levels of moderate to vigorous intensity for 30 minutes or more most days of the week is less than five percent among adults in the U.S. Low fitness levels are associated with inactivity and several risk factors for chronic disease. A key impediment to maintaining physical activity is motivation. However, finding ways to motivate people to be physically active at the levels necessary for increases in fitness have not met with much success. Individuals become bored with training regimens over time or find them less enjoyable if they do not employ strategies to maintain their motivation. Although group exercise leads to higher exercise adherence than individual exercise programs, structured group exercise programs present a problem for those with social physique anxiety and those who lack the time and/or resources to join an exercise group. Moreover, prior models of group exercise have rarely if ever introduced any real interdependence between exercisers (e.g., created teams whose progress and/or outcomes were mutually determined), which have been powerful motivators for continued effort. Exercise games have been marketed as a way to increase people's motivation to exercise by being entertaining and engaging and providing a means by which to interact with other players. However, there has been little attempt to analyze what game features and interpersonal interactions would best motivate people to use and continue exercising with these games. Our research is designed to determine whether recently documented motivation gains in task groups (dyads in particular) can be harnessed to improve peoples' motivation in interactive exercise games using a virtual (software-generated) partner. Exercising with a software-generated (SG) partner offers a number of advantages (e.g., availability, flexibility, reducing social physique anxiety) over using a live human partner. If peoples' motivation can be improved to increase the intensity and duration of exercise by participating with such a partner, they will realize better health outcomes than if they exercise alone. Although many exercise games involve competition among players, few take advantage of the potential of group dynamics to motivate play (and to achieve its associated health benefits). The specific aims of the proposed project are to 1) Develop the software to create SG exercise partners; 2) Test various design features of the SG partner within exercise video games to determine the most effective features for enhancing motivation to exercise; and 3) Test whether participating in exercises with an SG partner enhances participants' enjoyment in the activity, self-efficacy, and intention to exercise in the future. Results from this investigation will lead to future R01 applications that will examine the long-term effects of exercising with an SG partner, including under free-living conditions, expand the design features of the SG partner, and expand the target populations (e.g., those in exercise rehabilitation therapies, adolescents).